Replacement of incandescent lamps for the reason of environmental concern is currently being performed by energy saving fluorescent lamps and by solid state solutions, in particular light-emitting diodes (LEDs). While fluorescent lamps extract about 6 times more light per watt and have a lifetime of up to 10,000 hours, which is 10 times longer than incandescent lamps, a LED lamp requires 90% less energy than an incandescent lamp and 50% less than an energy saving fluorescent lamp, and it can burn up to 50,000 hours. Other advantages of LED lamps with respect to fluorescent lamps are in the instant switching on, the possibility of dimming and the use of environmental friendly components, which can be disposed as normal waste, since no mercury is present. The transition to LED based lighting is in full execution with respect to low lumen output bulbs.
In incandescent bulb replacement lamps based on LEDs, commonly referred to as “retrofit lamps” since these LED lamps are often designed to have the appearance of a traditional light bulb and to be mounted in conventional sockets etc., the light emitting filament wire is replaced with one or more LEDs. The atmosphere within the bulb may be air or helium. However, a problem with LED based retrofit lamps is the cooling of the LEDs. Overheating of LEDs can lead to reduced lifetime, decreased light output or failure of the LEDs. Due to inadequate cooling some types of lamps have so far not been possible to realize, in particular high lumen output LED lamps for replacement of incandescent lamps producing 60, 75 or 100 W.
Hence there is a need in the art for improved LED based lamps, capable of replacing incandescent light having high lumen output.